The Fenton reaction based on ROS generation in tumor cells is a new anti-cancer strategy that has emerged in recent years. However, the high-efficiency of Fenton reaction still faces problems such as low catalytic activity of metal ions and slightly insufficient of H₂O₂ content in cells. Traditional encapsulated-delivery strategies have effectively increased the total amount of reactants, but were also accompanied by insufficient reaction due to incomplete release. Therefore, it is crucial for the select and design of carrier. In this study, cellulose nanocrystals (CNCs) with large specific surface area were selected as carriers, and Au NPs was directly conjugated with high-reactivity Fe²⁺ as an ion-ligand bridge on the surface.The nanosystems deliver a large amount of highly reactive Fe²⁺ and DOX by surface loading of cellulose nanocrystals, which greatly improves ROS yield and promotes the application of Fenton reaction system in cancer therapy.